title: Potential of a no-touch pincer ablation procedure for small hepatocellular carcinoma that uses a multipolar radiofrequency ablation system: An experimental animal study.
abstract: OBJECTIVE
  Treatment of hepatocellular carcinoma located on the liver surface is frequently difficult because direct puncture of the tumor must be avoided during needle insertion. The aim of this study was to investigate the utility of a no-touch pincer ablation procedure that uses a multipolar radiofrequency ablation (RFA) system for a tumor located on the liver surface.
  
  
  METHODS
  The experimental animals were three pigs, and RFA was performed with two internally cooled bipolar electrodes. Three ablative procedures were compared: linear insertion at regular 13-mm intervals (pattern 1; virtual target tumor size, <10 mm); fan-shape insertion, maximum interval 20 mm (pattern 2; virtual target tumor size, <15 mm); and 25 mm (pattern 3; virtual target tumor size, <20 mm). All electrodes were inserted at a 30-mm depth. For patterns 1 and 2, ablation was performed on three other parts of the liver, and for pattern 3, ablation was performed on two other parts.
  
  
  RESULTS
  For the median transverse and longitudinal diameter to the shaft, with the pattern 1 procedure, the ablative areas were 32 mm × 30 mm, and with the pattern 2 procedure, the ablative areas were 27 mm × 30 mm with carbonization of the liver surface. In contrast, with the pattern 3 procedure, the ablative areas were 45 mm × 26 mm; however, the ablative margin did not reach the surface, and carbonization was not apparent.
  
  
  CONCLUSIONS
  The no-touch pincer ablation procedure (with an electrode interval of ≤20 mm) may be useful when performed with two internally cooled bipolar electrodes for small nodules that protrude from the liver surface.
authors.affiliation: Department of Hepatology, Toranomon Hospital, Tokyo, Japan; Okinaka Memorial Institute for Medical Research, Toranomon Hospital, Tokyo, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kawamura
authors.forename: Kenji
authors.initials: K
authors.lastname: Ikeda
authors.forename: Taito
authors.initials: T
authors.lastname: Fukushima
authors.forename: Tasuku
authors.initials: T
authors.lastname: Hara
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hosaka
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Saitoh
authors.forename: Hitomi
authors.initials: H
authors.lastname: Sezaki
authors.forename: Norio
authors.initials: N
authors.lastname: Akuta
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Suzuki
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Arase
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Kumada
keywords: bipolar; hepatocellular carcinoma; multipolar; no-touch ablation; radiofrequency ablation